Unit 6 Mendelian Genetics and Patterns of Inheritance Practice Test
1. Which of the following molecules is the subunit of DNA that links together to form strands of DNA?
A. a phosphate base
B. a nucleotide
C. a polymerase
D. a codon
2. Which of the following describes an allele whose characteristic phenotype is masked by the presence
of a second, different allele?
A. polygenic
B. codominant
C. recessive
D. dominant
3. AB blood type is an example of __________.
A. independent assortment
B. codominance
C. polygenic inheritance
D. incomplete dominance
4. Lupe grows pea plants in her garden. The pea plants have flowers that can be either purple or white,
with purple color being dominant to white color. The peas produced by Lupe's pea plants can also be
either round or wrinkled, with round peas being dominant to wrinkled peas.
Lupe crosses two pea plants that are heterozygous for both traits. If a gamete from this cross receives a
dominant allele for flower color, how does this influence the probability of the gamete receiving a
dominant allele for pea shape?
(*Assume that the genes for flower color and pea shape follow the Law of independent assortment.)
A. It decreases the probability that the gamete will receive a dominant allele for pea shape.
B. It increases the probability that the gamete will receive a dominant allele for pea shape.
C. It causes the gamete to be unable to receive a dominant allele for pea shape.
D. It has no effect on the probability of the gamete receiving a dominant allele for pea shape.
5. How does DNA help with the transfer of genetic material from parents to offspring?
A. DNA is mutated by a chemical passed to offspring to form proteins that express traits.
B. Proteins bind to DNA, which activates them and forces them to express certain traits.
C. Enzymes break down DNA, releasing amino acids that join to form proteins and express traits.
D. Genes in DNA code for the production of proteins, which cause traits to be expressed.
6. Punnett squares depict the genotypes of two parents and are used to predict the inherited traits of
offspring. Which of the following would be the missing predicted trait in the table below?
A. AO
B. OO
C. OA
D. AA
7. Sarah is doing an experiment on pea plants and has noticed that many pea plants have purple flowers
and many have white flowers.
Sarah crosses a homozygous white flower and a homozygous purple flower. The cross results in all
purple flowers.
What is true of the color of pea plants?
A. Purple flowers and white flowers are recessive to red.
B. Purple flowers are dominant to white flowers.
C. White flowers are dominant to purple flowers.
D. White flowers and purple flowers are codominant.
8. What is a gene?
A. any single amino acid in a multicellular organism
B. a sex cell that aids in organism reproduction
C. a characteristic of any organism
D. a set of instructions in the DNA sequence of an organism
9. ______ is a source of genetic variation that involves the swapping of sections of chromosomes during
meiosis.
A. Fertilization
B. Translation
C. Transcription
D. Crossing over
10. Which of the following cellular materials is solely composed of DNA and proteins?
A. mitochondria
B. ribosomes
C. chromosomes
D. Golgi complex
11. One possible form of a gene that codes for a particular trait is known as _______.
A. a chromosome
B. an allele
C. a phenotype
D. a genotype
12. After crossing-over as shown below, what would the sequence of genes be for each of the
chromatids?
A. ABCD, abcd, ABcd, abCD
B. ABCd, abCD, abcD, abCD
C. ABCD, abCD, abCd, abcD
D. ABab, CDCd, abab, CDcD
13. Human height is a polygenic trait. This means that the
A. trait is controlled by more than one pair of genes.
B. trait is controlled by the genes inherited from the father only.
C. trait is completely controlled by only one pair of genes.
D. trait is controlled by the genes inherited from the mother only.
14. During meiosis, diversity is achieved by the process of
I.
crossing over.
II. chromosome separation.
III. DNA replication.
A. II and III only
B. I and III only
C. I and II only
D. I, II, and III
15. The DNA of a cell is organized into structures. What are these structures called?
A. mitochondria
B. nuclei
C. chromosomes
D. vacuoles
16.
Rachel grows pea plants in her backyard. Some of the pea plants have purple flowers, whereas others
have white flowers. What does this indicate about Rachel's pea plants?
A. The pea plants have genetic variation.
B. The pea plants cannot reproduce.
C. The pea plants all have identical genes.
D. The pea plants can only reproduce asexually.
17. During meiosis, the process of crossing over results in new combinations of alleles due to
A. genetic material is removed during this process.
B. genetic material always mutates randomly during this process.
C. genetic material is exchanged between chromosomes during this process.
D. genetic material is added by a third chromosome during this process.
18. A certain type of flower has two alleles for color (blue, purple), and two alleles for stem height (tall,
short). A tall blue flower and a short purple flower are crossed, resulting in tall blue flowers, short blue
flowers, tall purple flowers, and short purple flowers.
What law does this example help to prove?
A. Law of Genetic Inheritance
B. Law of Multiple Alleles
C. Law of Segregation
D. Law of Independent Assortment
19. A recessive gene located on the X chromosome is the cause of color blindness in affected individuals.
Males are more likely to be colorblind than females because
A. males have only one copy of the X chromosome.
B. males have two copies of the X chromosome.
C. females have no copies of the X chromosome.
D. color blindness is associated with high testosterone levels.
20. Hereditary information is found in _______, which are located in the _______ of the cell.
A. genes; chromosomes
B. ribosomes; cytoplasm
C. nucleotides; vacuoles
D. mitochondria; endoplasmic reticulum
21. Fifty percent of the offspring produced by a cross between pea plants have seeds with a wrinkled (r)
appearance caused by the presence of a homozygous recessive gene. What were the genotypes of the
parents?
A. RR × Rr
B. Rr × Rr
C. Rr × rr
D. RR × rr
22.
Directions: Select each correct answer.
Examine the Punnett square below, which represents a cross between a male and a female pear tree.
B
B
B
?
?
b
?
?
What are the possible genetic variations of offspring in this cross? Choose all correct answers.
a. BB
b. Bb
c. bb
23. All cells contain DNA, which provides information for the cells to make
A. different kinds of proteins.
B. new types of genes.
C. new types of organisms.
D. different kinds of DNA.
24. What is the term used to describe the heritable, physical characteristics of a living organism?
A. phenotype
B. genotype
C. pedigree
D. allele
25. An organism's genotype can best be defined as its
A. inherited combination of alleles.
B. inherited physical appearance.
C. number of recessive genes.
D. number of chromosomal pairs.
26. A(n) _______ is a characteristic arising from genes located on chromosomes that are not genderdetermining.
A. autosomal trait
B. genotype
C. sex-linked trait
D. allele
27. Carla receives an allele for blue eyes from her mother, and an allele for brown eyes from her father.
If brown eye color is a dominant trait and blue eye color is a recessive trait, what can be determined
about the color of Carla's eyes?
A. Carla has blue eyes.
B. Carla's eye color can not be determined.
C. Carla has green eyes.
D. Carla has brown eyes.
28. It is possible for an organism to inherit a gene with two dominant alleles. What is a gene with two
dominant alleles that are expressed at the same time?
A. heterozygous
B. codominant
C. incompletely dominant
D. polygenic inheritance
29. Which of the following is the term for one possible form of the gene for a particular trait?
A. allele
B. codon
C. autosomal trait
D. sex-linked trait
30. According to Mendel's Law of Segregation, meiosis involves the separation of a parent organism's
alleles in order to form gametes. Since the alleles separate into different gametes, only one allele passes
from each parent on to an offspring. This segregation of alleles during meiosis
A. decreases the genetic variability of the offspring.
B. decreases the chance that an offspring will receive a dominant allele.
C. increases the genetic variability of the offspring.
D. increases the chance that an offspring will receive a dominant allele.
31. In pea plants, tall (T) plants are dominant over short (t) plants. If a heterozygous (Tt) pea plant is
crossed with a homozygous dominant (TT) pea plant, all of the resulting pea plants should be tall (TT or
Tt). Each plant will receive a dominant allele from the homozygous dominant plant, while they could
receive either a dominant or recessive allele from the heterozygous plant.
The fact that each plant gets only one allele from each parent plant is detailed in the Law of _______.
A. Independent Assortment
B. Multiple Alleles
C. Genetic Inheritance
D. Segregation
32. A student crosses two pea plants. One is homozygous dominant for axial flowers, and the other is
heterozygous for axial flowers. If the student examines 200 offspring pea plants, which of the following
is a reasonable result?
A. 47 with axial flowers, 153 with terminal flowers
B. 200 with axial flowers, 0 with terminal flowers
C. 149 with axial flowers, 51 with terminal flowers
D. 98 with axial flowers, 102 with terminal flowers
33. Guinea pig coat color is determined by a single gene. The allele for black coat color is dominant to
brown. In a cross between two black-haired guinea pigs, 20 offspring are born. If both parents were
heterozygous, probability would predict that approximately how many of the 20 offspring would have
brown hair?
A. 5
B. 10
C. 0
D. 15
34. A student crosses two true-breeding pea plants, one with green pods and the other with yellow
pods. If yellow is dominant over green, what phenotypic results will the student find in the F1
generation?
A. 75% yellow, 25% green
B. 75% green, 25% yellow
C. 100% yellow
D. 100% green
35. Trey goes to a rabbit farm to look at a litter of newborn rabbits. The newborns are all different
colors. They are gray, black, white, light brown, and dark brown.
What type of inheritance pattern are these rabbits likely displaying?
A. incomplete dominance
B. dominant-recessive
C. codominance
D. multiple alleles
36. An organism's genotype describes its specific combination of alleles. For example, an Aa genotype is
heterozygous for the A allele.
An organism's phenotype describes a visible trait, such as tall height, brown eyes, or black fur.
How does genotypic variation occur?
A. Genotypic variation only occurs when genetic mutations occur.
B. Genotypic variation occurs when alleles are randomly sorted during asexual reproduction.
C. Genotypic variation only occurs during binary fission.
D. Genotypic variation occurs when alleles are randomly sorted during sexual reproduction.
37.
Directions: Type your answer in the box. Use numerals, not words.
Hemophilia A is an X-linked recessive disease. If a mother without the disease and a father without the
disease have one son diagnosed with hemophilia, what is the probability (percent chance) that a future
daughter they have together will also be afflicted with hemophilia?
%
38. Mrs. Smith has blood type A. Her father has blood type A, and her mother has blood type B. If Mr.
Smith has blood type AB, what is the probability that they will have a child with blood type AB?
A. 25%
B. 50%
C. 100%
D. 0%
39. Which hereditary rule explains why a self-fertilizing parent that is heterozygous for the A locus (Aa)
can produce offspring that are AA or aa?
A. dominance
B. principle of independent assortment
C. codominance
D. principle of segregation
40. The genetic information that is passed from a parent to its offspring is found in _______.
A. hydrogen bonds
B. carbon atoms
C. amino acids
D. DNA molecules
41. During meiosis, homologous chromosomes frequently exchange portions of their DNA. This process
further increases the number of different genotypes that can appear in an offspring. What is the name
of this process?
A. genetic transfer
B. crossing-over
C. transduction
D. mutation
42.
Directions: Type your answer in the box.
The variation of kernel color in corn plants is an inherited trait. R is the dominant allele for red kernels in
a corn plant and r is the recessive allele for yellow kernels.
What is the probability that a corn plant with the genotype Rr crossed with a corn plant rr will have
offspring with the genotype rr? Express your answer as a fraction using numerals for numbers and / for
the fraction bar. Do not include spaces.
43. Body cell mutations cannot be passed on to offspring. This is because body cells do not contribute
genetic material to
A. non-mutant cells.
B. sex cells.
C. each other.
D. daughter cells.
44. An allele is one of the alternative forms of a gene that governs a trait. If a fern plant is heterozygous
for a particular trait, how can the alleles that control that trait be described?
A. one dominant, one recessive
B. two dominant
C. two recessive
D. three recessive, one dominant
45. The DNA sequences that make up the genetic code of an organism determine which traits the
organism will exhibit.
How are the instructions coded by DNA translated into an organism's physical traits?
A. Instructions coded by DNA sequences are translated into proteins which express an organism's
physical traits.
B. Instructions coded by DNA sequences are translated into nucleotides which express an
organism's physical traits.
C. DNA sequences that code for genetic instructions attach to phosphate groups that express an
organism's physical traits.
D. DNA sequences both code genetic instructions within an organism and express an organism's
physical traits.
46. Gregor Mendel developed several laws of heredity over the course of his genetic research. What
does the first law of heredity, the law of segregation, state about genes?
A. Alleles of different genes separate independently of one another during gamete formation.
B. Dominant alleles are always more likely to be inherited.
C. Mutations can only occur in heterozygous organisms.
D. Two alleles for a trait separate when gametes are formed.
Answers to Unit 6 Genetics Practice Test
1. B
2. C
3. B
4. D
5. D
6. B
7. B
8. D
9. D
10. C
11. B
12. C
13. A
14. C
15. C
16. A
17. C
18. D
19. A
20. A
21. C
22. -23. A
24. A
25. A
26. A
27. D
28. B
29. A
30. C
31. D
32. B
33. A
34. C
35. D
36. D
37. -38. A
39. D
40. D
41. B
42. -43. B
44. A
45. A
46. D